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61.
A. A. Stierle R. Upadhyay J. Hershenhorn G. A. Strobel G. Molina 《Cellular and molecular life sciences : CMLS》1991,47(8):853-859
Black Sigatoka is the most costly to control disease of bananas and plantains in the world. Currently, a worldwide search is underway either to find or to produce cultivars that are disease-resistant or-tolerant. Phytotoxins isolated from the pathogen might facilitate the discovery of such cultivars. Several aromatic compounds from liquid cultures ofMycosphaerella fijiensis, the causal agent of Black Sigatoka disease of bananas and plantains, have been isolated. The most abundant and phytotoxic of these compounds is 2,4,8-trihydroxytetralone, which induces necrotic lesions at 5 g/5 l in less than 12 h on sensitive cultivars of bananas. This compound exhibits host-selectivity that mimics that of the pathogen. Other phytotoxins isolated from this fungus, in lesser amounts, were juglone, the novel compound 2-carboxy-3-hydroxycinnamic acid, isoochracinic acid and 4-hydroxyscytalone. Some of the phytotoxins isolated are melanin shunt pathway metabolites, which makes this fungus unique among plant pathogens. 相似文献
62.
含铝高速钢中奥氏体非均匀长大的机制 总被引:2,自引:0,他引:2
M2AI和M2高速钢经一次和二次淬火后,奥氏体晶粒和未溶碳化物的定量研究表明,在高温r/f比值相同的条件下,由于淬火前原始组织的差别,可发生正常(均匀)和异常(非均匀)两类长大。根据异常粗晶形成初期的组织观察,提出了“连续-非连续”再结晶模式和“合并—推移”式的生长机制。提出了减轻或消除M2AI钢混晶的工艺原则。 相似文献
63.
刘金河 《厦门大学学报(自然科学版)》1990,29(4):472-474
不同组合巴西橡胶三合树在福建南部的生态条件下,其生长强度,生理代谢和抗逆能力都存在差异。本文中主要研究比较了几种橡胶三合树的生长强度,光合作用强度及其变化。研究结果表明,三合树的生长强度和光合强度明显比对照树高,不同组合三合树的生长强度和光合强度与它们的抗寒力成正相关。 相似文献
64.
H. Tsuchiya M. Sato M. Iinuma J. Yokoyama M. Ohyama T. Tanaka I. Takase I. Namikawa 《Cellular and molecular life sciences : CMLS》1994,50(9):846-849
Phytoalexins, defensive compounds produced by plants against microbial infections, were purified fromSophora exigua (Leguminosae) and their growth inhibitory effects on oral cariogenic bacteria were determined in vitro. Among three isolated compounds, 5,7,2,4-tetrahydroxy-8-lavandulylflavanone completely inhibited the growth of oral bacteria including primary cariogenic mutans streptococci, other oral streptococci, actinomycetes, and lactobacilli, at concentrations of 1.56 to 6.25 g/ml. 相似文献
65.
A. M. Fenyves M. Saxer K. Spanel-Borowski 《Cellular and molecular life sciences : CMLS》1994,50(2):99-104
Five cell types recently isolated from the bovine corpus luteum differed in their epithelioid morphology and their cytoskeleton, but shared common criteria of microvascular endothelial cells1,2. To give strong evidence for the separate entity, the growth rate of the 5 phenotypically different cells was studied. They were seeded at low density on day 0. Most of these cells were treated with 200 to 1000 U recombinant bovine interferon- (IFN-) for 3 days. The untreated remainder served as controls. Cell counts were made for all cultures on days 4, 7, 10 and 13. morphology: 13 d after treatment with IFN- senescent cells as well as intact cells occurred in cultures of cell types 1 to 4. Cultures of cell type 5 were apparently unchanged and resembled their untreated counterparts. Desminpositive cells in cultures of cell type 2 developed cell processes. Growth rate: In the absence of IFN-, the growth rate was high for cell types 3 and 4, moderate for cell type 1, and low for cell types 2 and 5. The presence of IFN- caused anti-proliferative effects. These were higher for cell types 3 and 4 than for cell types 1 and 2. IFN- could be cytotoxic on cell type 3. In contrast, the cytokine tended to support the cell growth of cell type 5. These findings substantiate the postulate that endothelial cells exhibiting separate morphology in culture also function differently. 相似文献
66.
报道了“桂丰三号”的主要植物学特征、农艺性状和生长发育特性.“桂丰三号”是一个无限生长型的中晚熟品种,主蔓长3.5~4.5m,其第15~20节开始着生花芽、第3~10节上共长出3~7条侧蔓.3月15日至6月30日期间,从播种到开花约需75天;7月10日至20日期间,从播种到开花约需50天.3月至7月20日期间,无论何时播种,其开花结荚盛期都在9月中旬至10月中下旬。单株结荚数30~50荚,荚长19cm,荚横断面呈正方型,每荚有15粒种子,老熟种子黄褐色、圆形,千粒重300g。嫩豆荚淡绿色,成熟豆荚黑褐色. 相似文献
67.
Thrombospondin (TSP) is a multifunctional glycoprotein which is synthesised by several cell types including osteoblasts, and incorporated into the extracellular matrix (ECM) of these cells. The function and regulation of TSP in bone is not clear. In this study, using a long term culture model of human osteoblast-like cells, we examined the distribution of TSP in the ECM and its modulation by added estradiol. In this model the osteoblast-like cells form a regular multilayer which continues to increase in depth up to 50 days post confluence. In the ECM of these cultures and in 19-week fetal bone, the bone markers osteocalcin and alkaline phosphatase were diffusely distributed in the matrix. In contrast, labelling for TSP was concentrated, confined to the banded collagen and its immediately adjacent ECM. This pattern of labelling resembled that of the growth factors transforming growth factor-I (TGF), and insulin-like growth factor-I (IGF-I), with which TSP label co-localised. Labelling intensities were comparable between fetal bone and the in vitro material for TSP, TGF and IGF-I. TSP label was present by 10 days post confluence, reached a maximum by 20 days, and declined slowly thereafter, a time course which was similar to that of IGF-I. Incubation of osteoblast-like cell cultures with 17 estradiol resulted in an increase in multilayer depth and a maximal 3-fold increase in TSP labeling at 30 days as well as approximately 2-fold increases for TGF and IGF-I. The dose-response relationship for these responses to estradiol treatment was biphasic with maximal increases at 10–10 M–10–11 M of added estradiol. Treatment with 17 estradiol produced labelling intensities that were not significantly different from controls. Studies with other cell types have suggested that TSP may be involved in modulation of growth factor activity. The similarities between TSP, TGF and IGF-I, in terms of their distribution and regulation by 17 estradiol treatment, may indicate a role for TSP in modulating bone cell proliferation and function through interaction with local growth factors. 相似文献
68.
69.
从几个籼稻品种不同发育阶段的幼穗分离出密度平均为22×105个/mL~46×105个/mL的原生质体。将这些原生质体包埋在藻酸钠颗粒里并分别在粳稻愈伤组织滋养下培养和没有愈伤组织滋养。在这两种培养条件下原生质体稳定,分裂频率分别达到484%和388%,群体存活率达到53%和47%,愈伤组织绿苗分化率达到716%和623%。这两种方法优于常用的琼脂糖包埋法和琼脂糖颗粒法。 相似文献
70.
王军 《安徽师范大学学报(自然科学版)》1998,21(3):292-297
本文报道了金寨县具维管束植物1881种,隶属于178科,753属;具陆栖脊椎动物185种,隶属于22目,61科。金寨县动植物资源特点具备丰富性、稀有性、古老性、过渡性和特有性。在天堂寨和马鬃岭两个自然保护区基础上,进一步扩大保护范围,加大保护力度,加强保护区建设。 相似文献